T-200 bass pedal problem fixed

[T-200]

Hi!</P>


Here I am again with one problem solved. I had the Eb bass pedal with no sustain or legato while all other pedals worked fine.</P>


I figured out that the problem must be in the pedal keyer board and specifically in the components only this pedal uses, because if the fault was in the common section of the keyer board or in the divider board it would affect to all pedals.</P>


That simplified the task. There are only 7 parts involved andmost probable dead ones would be D751 diode (1N3605), Q753 transistor (BC548) and most of all C751 capacitor ( an old white Mallory 10uF/15V electrolytic...). Because the keyer board is very hard to reach I decided to change all three of them just to make sure, because the parts cost a few cents a piece. </P>


Now both the sustain and the legato work fine and I can use my favorite transition chord sequencewhen playing in D minor key: </P>


Gm6/E - A7b5/Eb - Dm7/D, very melancholic, like most of us Finns are ... [;)]</P>


This is just to encourage other T owners to figure out the secrets of the T-series. I think the organs this age need more and more component changes as time goes by...</P>


Cheers, Jussi</P>

[Brendon Wright]

Re: T-200 bass pedal problem fixed



Heya Jussi!</P>


I started work on replacing the cap cans last night, since I was under the chassis for something else. I haven't finished because I have anotherpuzzle to solve first:</P>


Since you've fiddled with the keyer boards you might have some insight for me....</P>


I've lost the pedals on keyer boards 2 and 3. Can't find why. Haven't found a broken wire yet, also haven't taken the boards out yet to see if some cap has popped.</P>


Any sneaking suspicions?</P>


Cheers!</P>


-Brendoooooon</P>

[SimonB]

Re: T-200 bass pedal problem fixed



Hi Brendon,
There is very likelya break in thepedal switch dasy-chain. Check for +15V at pin 1 on board 1 and pin 6 on board 2.Hopefully, it'll just bethat wire broken off or it could be a bad or dirty contact on S755.</P>


Probably a good idea to clean all the pedal switch contacts.while you're at it, mabe even put some fresh grease on all the actuators (you'll see the dried up old yellow stuff).</P>


Simon</P>

[T-200]

Re: T-200 bass pedal problem fixed



Join the club Brendon, that happened to me, too!</P>


Simon is probably right, I easily ripped some of the thin wires loose with the amp chassis because it's very small space between the chassis and the "daisy chain". The wires are soldered in small hollow pins and at first it looks like they are OK, but when you start wiggling them you maynotice that some are loose. Very tricky to re-solder, if you want it neat. Melt the solder in the pinhole, suck the broken wire from it, solder again... no way. I just soldered the wires on the sides of the pins, and it works fine...</P>


Sorry for my late answer, but I've been on the road again.</P>


Jussi</P>

[Brendon Wright]

Re: T-200 bass pedal problem fixed



Ahh!</P>


Cheers a bunch Simon and Jussi!</P>


I identified the wires that carry to the 2nd board (and from there the third) so I'll measure 'em at lunch time. They all looked good last night but the offender was obviously past wiggling to remake the connection.</P>


Watch out Jussi, what did you Mother tell you about going on the road!?!</P>


-B</P>

[T-200]

Re: T-200 bass pedal problem fixed



Cheers Brendon,</P>


You know that I never listen to mothers. They "don't let their babies grow up to be cowboys, don't let 'em pick guitars and drive 'em old trucks,make 'em be doctors and lawyers and such".And I want to be "on the road again" with myvan all week so I can go back home for the weekend to do some "T-series scientific experiments..."[8-|]</P>


Ahem... Hope you find the loose wires in the key switch boards. I think it's worthwhile also toclean or wigglethat 15-pin connector on the side of the boards where the daisychains grow...</P>


OK, maybe it's time to bed...</P>


Jussi</P>

[Brendon Wright]

Re: T-200 bass pedal problem fixed



Ahh! Fairey nuff!</P>


Arthur Dent: "It's at moments like these when I'm in a Vogon airlock and about to die of asphyxiation in deep space that I REALLY WISH I'd listened to what my mother told me!"</P>


Ford Prefect: "Why, what did she say?"</P>


Arthur: "I DON'T KNOW. I didnlt listen!!"</P>


We know that "T" stands for Triffic!, eh!</P>


Have a nifty drive, I'll see you back on the T ranch with a T bone steak and a cup of T when you get back!</P>


Steer well!</P>


-B</P>

[Brendon Wright]

Re: T-200 bass pedal problem fixed



Ped's've come right.</p>

Couldn't find a broken wire, but there was something intermittent actually under board 1.</p>

It was like a piece of dirt was shorting a contact just enough to cancel out the top 8 pedals. Tapping the board would set it on and off, eventually it seemed to have stopped doing it... I'll take the boards out if it returns, otherwise I'll leave it and get on with other things.</p>

....filters, compression.... and one of these days I need to put the felts in under the pedals!!!</p>

Cheers!</p>

-Brendoooon</p>